1. Field of the Invention
The present invention relates to an automotive alternator mounted to an automotive vehicle such as a passenger car or a truck, for example, to a stator winding assembly of the automotive alternator, and to a method of manufacture for the stator winding assembly.
2. Description of the Related Art
To reduce the size and increase the output of alternators driven by internal combustion engines, it is necessary to increase the space factor of electrical conductors housed within magnetic circuits of a stator, and to line up and increase the density of crossover portions (coil end portions) of a stator winding, and various improvements have been proposed, as for example in Japanese Patent Laid-Open No. HEI 11-164506.
FIGS. 27 and 28 are perspectives from a front end and a rear end, respectively, of part of a stator winding of a conventional alternator of this type, and FIG. 29 is a perspective showing a construction of a conductor segment used in the stator winding of the conventional alternator shown in FIGS. 27 and 28.
In FIGS. 27 to 29, a stator 90 is constituted by a stator core 91, a stator winding 92 constituted by a number of electrical conductors disposed inside slots 91a formed in the stator core 91, and insulators 93 providing electrical insulation between the stator core 91 and the electrical conductors.
In the stator core 91 of this conventional example, ninety-six slots 91a are disposed at even pitch so as to house two three-phase alternating current windings such that the number of slots housing each phase portion of the three-phase alternating current windings corresponds to the number of magnetic poles in a rotor. Four electrical conductors are housed within each of the slots 91a so as to line up in one row in a radial direction, and these electrical conductors are connected in a predetermined winding pattern to form the stator winding 92. Here, a first position, a second position, a third position, and a fourth position in a radial direction from an inner circumferential side inside the slots 91a in which the electrical conductors are housed will be called a first address, a second address, a third address, and a fourth address, respectively.
Large segments 95 and small segments 96 are formed by bending short lengths of a conductor such as copper into general U shapes in which pairs of straight portions 95a and 96a are linked by turn portions 95b and 96b. The small segments 96 are inserted one at a time from a rear end into pairs of slots 91a six slots apart (a pitch of one magnetic pole). Similarly, the large segments 95 are inserted one at a time from the rear end into pairs of slots 91a six slots apart (a pitch of one magnetic pole). Then, end portions of the large segments 95 and the small segments 96 extending outwards at a front end are joined to each other to constitute the stator winding 92.
More specifically, in pairs of slots 91a six slots apart, the small segments 96 are inserted from the rear end into the second address within first slots 91a and into the third address within second slots 91a, and the large segments 95 are inserted from the rear end into the first address within the first slots 91a and into the fourth address within the second slots 91a. Thus, within each of the slots 91a, two straight portions 95a of the large segments 95 and two straight portions 96a of the small segments 96 are disposed to line up in a row of four in a radial direction.
Then, end portions 95c of the large segments 95 extending outwards at the front end from the first address within the first slots 91a are joined to end portions 96c of the small segments 96 extending outwards at the front end from the second address within the second slots 91a six slots away in a clockwise direction from the first slots 91a. In addition, the end portions 95c of the large segments 95 extending outwards at the front end from the fourth address within the first slots 91a are joined to the end portions 96c of the small segments 96 extending outwards at the front end from the third address within the second slots 91a six slots away in a counter-clockwise direction from the first slots 91a. Thus, two winding sub-portions are formed, which are lap windings having two turns per lap. These two winding sub-portions are connected in series to form one winding phase portion having four turns.
Similarly, a total of six winding phase portions each having four turns are formed by offsetting by one slot at a time the positions of the slots into which the large segments 95 and the small segments 96 are inserted. Then, three each of these winding phase portions are connected into each of the two three-phase alternating current windings which constitute the stator winding 92.
In the conventional stator 90 constructed in this manner, at the rear end of the stator core 91, the turn portions 95b of the large segments 95 are disposed so as to cover outer circumferential sides of the turn portions 96b of the small segments 96 inserted into the same pairs of slots 91a. As a result, the turn portions 95b and 96b are disposed circumferentially to constitute a rear-end coil end group.
At the front end of the stator core 91, on the other hand, joint portions formed by joining the end portions 95c of the large segments 95 extending outwards at the front end from the first address within the first slots 91a and the end portions 96c of the small segments 96 extending outwards at the front end from the second address within the second slots 91a six slots away, and joint portions formed by joining the end portions 95c of the large segments 95 extending outwards at the front end from the fourth address within the first slots 91a and the end portions 96b of the small segments 96 extending outwards at the front end from the third address within the second slots 91a six slots away are disposed to line up radially. As a result, joint portions formed by joining the end portions 95c and 96c to each other are disposed circumferentially in two rows in a radial direction to constitute a front-end coil end group.
Because the stator winding 92 of the conventional alternator is constructed by inserting the large segments 95 and the small segments 96 formed by bending the short lengths of conductor into general U shapes into the slots 91a of the stator core 91 from the rear end and joining together the end portions of the segments extending outwards at the front end as explained above, one problem has been that a large number of the large segments 95 and the small segments 96 must be inserted into the slots 91a of the stator core 91 and end portions thereof must be joined one by one, significantly reducing workability and decreasing mass-producibility.
In addition, in order to join the end portions 95c of the large segments 95 and the end portions 96c of the small segments 96, it is necessary to clamp a portion of each of the end portions 95c and 96c together using a jig, and another problem has been that it is necessary to extend the segments out by an extra amount from the stator coil 91 to allow for the clamping, preventing the stator 90 from being reduced in size.
In the conventional stator 90, because the end portions 95c and 96c are joined to each other by clamping portions thereof in a jig and welding the end portions 95c and 96c together, the height of the coil ends is increased, and the large segments 95 and the small segments 96 are softened by temperature increases during welding, thereby causing rigidity of the stator to be decreased. As a result, other problems have been that when the conventional stator 90 is mounted to an alternator, coil leakage reactance in the coil end portions is increased to cause output to deteriorate, wind resistance is increased to exacerbate wind noise, and rigidity of the stator is reduced to exacerbate magnetic noise.
The present invention aims to solve the above problems and an object of the present invention is to provide a winding assembly for an alternator and a method of manufacture therefor enabling mass-producibility to be improved and size to be reduced.
Another objective is to provide an alternator enabling coil end height to be lowered, enabling the number of weld portions on the coil ends to be decreased, and enabling deterioration in output, wind noise and magnetic noise to be suppressed.
In order to achieve the above object, according to one aspect of the present invention, there is provided an alternator including:
a stator having a cylindrical stator core formed with a plurality of slots extending axially at a predetermined pitch in a circumferential direction, and a stator winding installed into the stator core; and
a rotor for forming north-seeking (N) and south-seeking (S) poles about a rotational circumference, the rotor being disposed on an inner circumferential side of the stator core, wherein
the stator winding comprises a plurality of winding sub-portions in each of which a strand of wire formed from a continuous wire is wound so as to alternately occupy an inner layer and an outer layer in a slot depth direction within the slots at intervals of a predetermined number of slots by folding over the strand of wire outside the slots at end surfaces of the stator core and form a lap winding having two turns in each lap.
Four of the strands of wire constituting the winding sub-portions may be housed so as to line up in each of the slots so as to occupy a first layer, a second layer, a third layer, and a fourth layer in a slot depth direction;
turn portions formed by folding the strands of wire over outside the slots at a first end surface of the stator core may be disposed circumferentially to form two rows in a radial direction; and
turn portions formed by folding the strands of wire over outside the slots at a second end surface of the stator core may be disposed circumferentially to form two layers in an axial direction.
In each of slot pairs in which first and second slots forming each of the slot pairs are a predetermined number of slots apart:
the strand of wire housed in the first layer inside the first slot may be folded over outside the slots at the first end surface of the stator core and housed in the second layer inside the second slot;
the strand of wire housed in the third layer of the first slot may be folded over outside the slots at the first end surface of the stator core and housed in the fourth layer of the second slot;
the strand of wire housed in the third layer inside the first slot may be folded over outside the slots at the second end surface of the stator core and housed in the second layer inside the second slot; and
the strand of wire housed in the fourth layer of the first slot may be folded over outside the slots at the second end surface of the stator core and housed in the first layer of the second slot.
The strands of wire may be installed two at a time into slot sets constituted by slot groups disposed a predetermined number of slots apart, the two strands of wire installed in each of the slot sets constituting a first strand of wire and a second strand of wire, and
the stator winding may be composed of a plurality of stator winding phase portions, each of the stator winding phase portions comprising:
a first winding sub-portion constructed by joining first and second end portions of the first strand of wire extending outwards outside the slots at the second end surface of the stator core from the fourth layer in the first slot of a first pair and the first layer in the second slot of the first pair, the first pair being one pair of the slot pairs constituting each of the slot sets; and
a second winding sub-portion constructed by joining first and second end portions of the second strand of wire extending outwards outside the slots at the second end surface of the stator core from the third layer in the first slot of the first pair and the second layer in the second slot of the first pair,
wherein each of the stator winding phase portions is constructed by connecting the first and second winding sub-portions in series by crossover connecting the first strand of wire extending outwards outside the slots at the second end surface of the stator core from the fourth layer in the first slot of a second pair, and the second strand of wire extending outwards from the outside of the slots at the second end surface of the stator core from the second layer in the second slot of the second pair, the second pair being another pair of the slot pairs constituting each of the slot sets, and
wherein the second strand of wire extending outwards at the second end surface of the stator core from the third layer in the first slot of the second pair, and the first strand of wire extending outwards at the second end surface of the stator core from the first layer in the second slot of the second pair constitute a neutral point,and an output wire of the stator winding phase portion, respectively.
The strands of wire may be installed two at a time into slot sets constituted by slot groups disposed a predetermined number of slots apart, the two strands of wire installed in each of the slot sets constituting a first strand of wire and a second strand of wire, and the stator winding may be composed of a plurality of stator winding phase portions, each of the stator winding phase portions being constructed by a first and second winding sub-portions which are connected in series by joining a first end portion of the first strand of wire extending outwards outside the slots at the second end surface of the stator core from the fourth layer in the first slot of a first pair to a second end portion of the second strand of wire extending outwards outside the slots at the second end surface of the stator core from the second layer in the second slot of the first pair, and joining a first end portion of the second strand of wire extending outwards outside the slots at the second end surface of the stator core from the third layer in the first slot of the first pair to a second end portion of the first strand of wire extending outwards outside the slots at the second end surface of the stator core from the first layer in the second slot of the second pair, the first pair being one pair of the slots pair constituting each of the slot sets, wherein the second strand of wire extending outwards at the first end surface of the stator core from the third layer in the first slot of a second pair and from the fourth layer in the second slot of the second pair is cut to constitute a neutral point and an output wire of the stator winding phase portion, the second pair being another pair of the slot pairs constituting each of the slot sets.
In each of slot pairs in which first and second slots forming each of the slot pairs are a predetermined number of slots apart:
the strand of wire housed in the second layer inside the first slot may be folded over outside the slots at the first end surface of the stator core and housed in the first layer inside the second slot;
the strand of wire housed in the third layer of the first slot may be folded over outside the slots at the first end surface of the stator core and housed in the fourth layer of the second slot;
the strand of wire housed in the second layer inside the first slot may be folded over outside the slots at the second end surface of the stator core and housed in the third layer inside the second slot; and
the strand of wire housed in the fourth layer of the first slot may be folded over outside the slots at the second end surface of the stator core and housed in the first layer of the second slot.
The strands of wire may be installed two at a time into slot sets constituted by slot groups disposed a predetermined number of slots apart, the two strands of wire installed in each of the slot sets constituting a first strand of wire and a second strand of wire, and
the stator winding may be composed of a plurality of stator winding phase portions, each of the stator winding phase portions comprising:
a first winding sub-portion constructed by joining first and second end portions of the first strand of wire extending outwards outside the slots at the second end surface of the stator core from the fourth layer in the first slot of a first pair and the first layer in the second slot of the first pair, the first pair being one pair of the slot pairs constituting each of the slot sets; and
a second winding sub-portion constructed by joining first and second end portions of the second strand of wire extending outwards outside the slots at the second end surface of the stator core from the second layer in the first slot of the first pair and the third layer in the second slot of the first pair,
wherein each of the stator winding phase portions is constructed by connecting the first and second sub-portions in series by crossover connecting the second strand of wire extending outwards outside the slots at the first end surface of the stator core from the third layer in the first slot of a second pair, and the first strand of wire extending outwards from the outside of the slots at the first end surface of the stator core from the first layer in the second slot of the second pair, the second pair being another pair of the slot pairs constituting each of the slot sets, and
wherein the first strand of wire extending outwards at the first end surface of the stator core from the second layer in the first slot of the second pair, and the second strand of wire extending outwards at the first end surface of the stator core from the fourth layer in the second slot of the second pair constitute a neutral point and an output wire of the stator winding phase portion, respectively.
Four of the strands of wire constituting the winding sub-portions may be housed so as to line up in each of the slots so as to occupy a first layer, a second layer, a third layer, and a fourth layer in a slot depth direction;
turn portions formed by folding the strands of wire over outside the slots at a first end surface of the stator core may be disposed circumferentially to form two rows in a radial direction; and
turn portions formed by folding the strands of wire over outside the slots at a second end surface of the stator core may be disposed in one row circumferentially.
According to another aspect of the present invention, there is a winding assembly for an alternator, the winding assembly including a winding group composed of 2n winding sub-portions disposed at a pitch of p, each of the winding sub-portions being constructed by folding and bending one strand of wire formed from a continuous wire into a pattern, the pattern having:
first straight portions disposed at a pitch of 2np;
second straight portions disposed at the pitch of 2np being offset by an amount w to a first side in a width direction from the first straight portions and offset by an amount np forwards relative to a direction of disposal of the first straight portions;
third straight portions disposed at the pitch of 2np being offset by the amount w to the first side in the width direction from the second portions and offset by the amount np backwards relative to the direction of disposal of the second straight portions;
fourth straight portions disposed at the pitch of 2np being offset by the amount w to the first side in the width direction from the third straight portions and offset by the amount np forwards relative to the direction of disposal of the third straight portions;
first turn portions linking first ends of the first straight portions to first ends of the second straight portions offset by the amount np forwards relative to the direction of disposal of the first straight portions;
second turn portions linking second ends of the second straight portions to second ends of the third straight portions offset by the amount np backwards relative to the direction of disposal of the second straight portions;
third turn portions linking first ends of the third straight portions to first ends of the fourth straight portions offset by the amount np forwards relative to the direction of disposal of the third straight portions; and
fourth turn portions linking second ends of the fourth straight portions to second ends of the first straight portions offset by the amount np forwards relative to the direction of disposal of the fourth straight portions, wherein
the winding sub-portions are disposed parallel to each other at the pitch of p in the direction of disposal such that the first to fourth straight portions form four layers in the width direction,
the first turn portions are disposed parallel to each other at the pitch of p and the third turn portions are disposed parallel to each other at the pitch of p such that the first turn portions and the third turn portions form two rows in the direction of disposal, and
the second turn portions are disposed parallel to each other at the pitch of p and the fourth turn portions are disposed parallel to each other at the pitch of p such that the second turn portions and the fourth turn portions form two layers in a longitudinal direction of the straight portions.
According to another aspect of the present invention, there is a winding assembly for an alternator, the winding assembly comprising a winding group composed of 2n winding sub-portions disposed at a pitch of p, each of the winding sub-portions being constructed by folding and bending one strand of wire formed from a continuous wire into a pattern, the pattern having:
first straight portions disposed at a pitch of 2np;
second straight portions disposed at the pitch of 2np being offset by an amount w to a first side in a width direction from the first straight portions and offset by an amount np forwards relative to a direction of disposal of the first straight portions;
third straight portions disposed at the pitch of 2np being offset by the amount w to the first side in the width direction from the second portions and offset by the amount np forwards relative to the direction of disposal of the second straight portions;
fourth straight portions disposed at the pitch of 2np being offset by the amount w to the first side in the width direction from the third straight portions and offset by the amount np backwards relative to the direction of disposal of the third straight portions;
first turn portions linking first ends of the first straight portions to first ends of the second straight portions offset by the amount np forwards relative to the direction of disposal of the first straight portions;
second turn portions linking second ends of the second straight portions to second ends of the third straight portions offset by the amount np forwards relative to the direction of disposal of the second straight portions;
third turn portions linking first ends of the third straight portions to first ends of the fourth straight portions offset by the amount np backwards relative to the direction of disposal of the third straight portions; and
fourth turn portions linking second ends of the fourth straight portions to second ends of the first straight portions offset by the amount np forwards relative to the direction of disposal of the fourth straight portions, wherein
the winding sub-portions are disposed parallel to each other at the pitch of p in the direction of disposal such that the first to fourth straight portions form four layers in the width direction,
the first turn portions are disposed parallel to each other at the pitch of p and the third turn portions are disposed parallel to each other at the pitch of p such that the first turn portions and the third turn portions form two rows in the direction of disposal, and
the second turn portions are disposed parallel to each other at the pitch of p and the fourth turn portions are disposed parallel to each other at the pitch of p such that the second turn portions and the fourth turn portions form two layers in a longitudinal direction of the straight portions.
According to another aspect of the present invention, there is a method of manufacture for a winding assembly for an alternator, the method including steps of:
disposing a group of 2n straight strands of wire at a pitch p in a first plane;
forming a lightning-bolt shaped pattern composed of a plurality of basic patterns by folding and bending the group of strands of wire in the plane, each of the basic patterns comprising:
first straight portions having a length l0;
second straight portions having the length l0 being linked to the first straight portions by first inclined portions having a length 10, the second straight portions being offset by an amount np to a first side in a direction of disposal of the strands of wire relative to the first straight portions;
third straight portions having the length l0 being linked to the second straight portions by second inclined portions having the length l1, the third straight portions being offset by the amount np to a second side in a direction of disposal of the strands of wire relative to the second straight portions; and
fourth straight portions having the length l0 being linked to the third straight portions by third inclined portions having the length 11, the fourth straight portions being offset by the amount np to the first side in a direction of disposal of the strands of wire relative to the third straight portions,
wherein the lightning-bolt shaped pattern is constructed by repeating the basic pattern a predetermined number of times by offsetting the basic pattern to the first side in the direction of disposal of the strands of wire by fourth inclined portions having a length l2, the length l2 being greater than the length l1;
forming a flattened cylindrical body by folding over the group of strands of wire formed into the lightning-bolt shaped pattern in a first direction at central portions of the first and the third inclined portions, the cylindrical body being constructed by helically winding the group of strands of wire such that the second and third straight portions linked by the second inclined portions and the first and fourth straight portions linked by the fourth inclined portions alternately occupy the first plane and a second plane; and
forming a winding group by folding over the cylindrical body at central portions of the second and the fourth inclined portions in a second direction such that the second and the third straight portions face each other, wherein
the first to fourth straight portions are disposed parallel to each other at the pitch of p in the direction of disposal such that the first to fourth straight portions form four layers in the width direction,
first turn portions formed by folding over the group of strands of wire at the first inclined portions are disposed parallel to each other at the pitch of p and third turn portions formed by folding over the group of strands of wire at the third inclined portions are disposed parallel to each other at the pitch of p such that the first turn portions and the third turn portions form two rows in the direction of disposal, and
second turn portions of the strands of wire formed by folding over the cylindrical body at the second inclined portions are disposed parallel to each other at the pitch of p and the fourth turn portions of the strands of wire formed by folding over the cylindrical body at the fourth inclined portions are disposed parallel to each other at the pitch of p such that the second turn portions and the fourth turn portions form two layers in a longitudinal direction of the straight portions.
According to another aspect of the present invention, there is a method of manufacture for a winding assembly for an alternator, the method including steps of:
disposing a group of 2n straight strands of wire at a pitch p in a first plane;
forming a lightning-bolt shaped pattern composed of a plurality of basic patterns by folding and bending the group of strands of wire in the plane, each of the basic patterns comprising:
first straight portions having a length l0;
second straight portions having the length l0 being linked to the first straight portions by first inclined portions having a length l1, the second straight portions being offset by an amount np to a first side in a direction of disposal of the strands of wire relative to the first straight portions;
third straight portions having the length l0 being linked to the second straight portions by second inclined portions having the length l1, the third straight portions being offset by the amount np to the first side in a direction of disposal of the strands of wire relative to the second straight portions; and
fourth straight portions having the length l0 being linked to the third straight portions by third inclined portions having the length l1, the fourth straight portions being offset by the amount np to a second side in a direction of disposal of the strands of wire relative to the third straight portions,
wherein the lightning-bolt shaped pattern is constructed by repeating the basic pattern a predetermined number of times by offsetting the basic pattern to the first side in the direction of disposal of the strands of wire by fourth inclined portions having a length l2, the length l2 being greater than the length l1;
forming a flattened cylindrical body by folding over the group of strands of wire formed into the lightning-bolt shaped pattern in a first direction at central portions of the first and the third inclined portions, the cylindrical body being constructed by helically winding the group of strands of wire such that the second and third straight portions linked by the second inclined portions and the first and fourth straight portions linked by the fourth inclined portions alternately occupy the first plane and a second plane; and
forming a winding group by folding over the cylindrical body at central portions of the second and the fourth inclined portions in a second direction such that the second and the third straight portions face each other, wherein
the first to fourth straight portions are disposed parallel to each other at the pitch of p in the direction of disposal such that the first to fourth straight portions form four layers in the width direction,
first turn portions formed by folding over the group of strands of wire at the first inclined portions are disposed parallel to each other at the pitch of p and third turn portions formed by folding over the group of strands of wire at the third inclined portions are disposed parallel to each other at the pitch of p such that the first turn portions and the third turn portions form two rows in the direction of disposal, and
second turn portions of the strands of wire formed by folding over the cylindrical body at the second inclined portions are disposed parallel to each other at the pitch of p and the fourth turn portions of the strands of wire formed by folding over the cylindrical body at the fourth inclined portions are disposed parallel to each other at the pitch of p such that the second turn portions and the fourth turn portions form two layers in a longitudinal direction of the straight portions.